CN1612488A - Radio frequency receiving channel automatic gain control method - Google Patents

Abstract

The invention discloses a method for automatic gain control of a radio frequency receiving channel. The method needs to set threshold values A and B in advance, and A is greater than B, and further includes: a. judging whether the output signal power of the radio frequency receiving channel is greater than the threshold value A , if greater, reduce the output signal power of the radio frequency receiving channel by X, and, X is greater than 0 and less than the difference between A and B, return to step a, otherwise, perform step b; b. determine whether the input signal power of the radio frequency receiving channel is is less than the threshold value B, if less, increase the output signal power of the radio frequency receiving channel by X, otherwise, do not adjust the output signal power, and return to step a. The invention reduces the automatic gain of the radio frequency receiving channel, so that when the input signal power of the radio frequency receiving channel fluctuates, the problem of frequent switching of the output signal power up and down is avoided, and the method is simple and reliable.

Description

A method for automatic gain control of radio frequency receiving channel

technical field

The invention relates to a gain control technology, in particular to a method for controlling automatic gain of a radio frequency receiving channel.

Background technique

Referring to Fig. 1, the wireless communication receiving system includes an antenna, a radio frequency receiving channel and a data signal processing unit. In the wireless communication receiving system, the radio frequency receiving channel processes the electromagnetic signal induced by the antenna, and the processed signal is then digitally processed. In the case of relatively high receiving dynamic requirements, the radio frequency receiving channel often adopts automatic gain control (AGC) technology, which can reduce the dynamic requirements of the A/D converter.

Referring to FIG. 2 , the receiver AGC control model includes a receiving front end 201 , a controllable gain device 202 , a radio frequency amplification unit 203 , an A/D conversion unit 204 , a digital signal processing unit 205 and a received signal strength calculation module 206 . In the initial state, the gain of the controllable gain device 202 is 1. After the receiving front end 201 receives the radio frequency signal sent by the antenna, the radio frequency signal is input into the radio frequency amplifying unit 203, and the radio frequency signal is input to the A/D converter 204 after being amplified, and converted into a digital signal by the A/D converter 204, the digital signal The signal is then input to the digital signal processing unit 205 for processing; at the same time, two thresholds A and B are set in the control algorithm of the received signal strength calculation module 206, and A>B, the received signal strength calculation module 206 utilizes digital signal processing The digital signal output by unit 205 calculates the strength of the received signal at point D. If the signal at point D is greater than the threshold value A, adjust the controllable gain device to reduce the radio frequency channel gain. If the signal at point D is less than the threshold value B, then Adjusting the controllable gain device increases the gain of the radio frequency channel.

The basic control scheme of the control model shown in FIG. 2 is shown in FIG. 3 , where the horizontal axis represents the input signal power of the receiving front end, and the vertical axis represents the output signal power of the radio frequency receiving channel. When the input signal of the receiving front end reaches the thermal noise level of the receiver, the output signal power of the radio frequency receiving channel is D value.

The basic control principle is: two thresholds A and B are set in the control algorithm of the received signal strength calculation module 206, and A>B, and the received signal strength calculation module 206 continuously detects the output signal power of the radio frequency receiving channel. In the (P1, P2) interval, when the input signal power of the receiving front end increases continuously, the output signal power of the RF receiving channel also increases continuously. When the input signal power of the receiving front end increases to the threshold value A, adjust the output signal Power, reduce the output signal power by A-B, and the output signal power reaches the threshold value B; when the input signal power of the receiving front end is less than the threshold value B, adjust the output signal power, increase the output signal power of the RF receiving channel by A-B, and output The signal power reaches the threshold value A. When the input signal power of the receiving front end reaches the points P2, P3, and P4 shown in the figure, the gain of the radio frequency channel will be adjusted once.

According to the above analysis, when the system has no service, the input signal power of the receiving front end remains unchanged, and the gain of the radio frequency channel remains unchanged. As the traffic increases, when the input signal power reaches P3 and P4 points, it is necessary to adjust the radio frequency channel gain through the module 202 .

It can be seen from the above that if the input signal power of the receiving front end is unstable at points P2, P3, P4, and P5, that is, when it fluctuates up and down, it will cause frequent switching of the gain. If the gain switching step is large, it will affect the reception of the receiving front end. Signal.

Contents of the invention

The purpose of the present invention is to provide a method for controlling the automatic gain of the radio frequency receiving channel, which can avoid frequent changes of the radio frequency channel gain due to the fluctuation of the input signal power of the receiving front end.

A method for controlling the automatic gain of a radio frequency receiving channel provided by the present invention includes:

a. Determine whether the current output signal power of the radio frequency receiving channel is greater than the threshold value A, if greater, then reduce the output signal power of the radio frequency receiving channel by X, and, X is greater than 0 and less than the difference between A and B, return to step a, Otherwise, go to step b;

b. judge whether the output signal power of the radio frequency receiving channel is less than the threshold value B, if less than, then increase the output signal power of the radio frequency receiving channel by X, and return to step a, otherwise, do not process and return to step a.

Said X is equal to one-half times the difference between A and B.

The invention reduces the adjustment amount of the radio frequency channel gain, so that when the input signal power of the radio frequency receiving channel fluctuates, the problem of frequent switching of output signal power up and down is avoided, and the method is simple and reliable.

Description of drawings

Figure 1 is a schematic diagram of the principle of a wireless receiving channel;

FIG. 2 is a schematic diagram of the principle of the wireless receiving channel AGC in the prior art;

Fig. 3 is the characteristic diagram of AGC principle control radio frequency receiving channel output in the prior art;

Fig. 4 is the schematic flow chart that realizes the method of the present invention;

Fig. 5 is a characteristic diagram of controlling the output of the radio frequency receiving channel according to a specific embodiment of the method of the present invention.

Detailed ways

In order to make the object, technical solution, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

Referring to shown in Figure 4, realizing the method of the present invention comprises the following steps:

Step 401, the radio frequency receiving channel continuously receives signals, and it is judged whether the output signal power of the radio frequency receiving channel is greater than the threshold value A, if greater, perform step 402, otherwise, perform step 403;

Step 402, reduce the output signal power of the radio frequency receiving channel by X, 0<X<A-B, return to step 401;

Step 403, judging whether the output signal power is less than the threshold value B, if less, then execute step 404, otherwise, return to step 401;

Step 404 , increase the output signal power of the radio frequency receiving channel, and return to step 401 .

Specific embodiments are given below and the technical solutions of the present invention are described in detail in combination with FIG. 2 and FIG. 5 .

Referring to FIG. 5 , A and B are two power thresholds set in the received signal strength calculation module 206 . P3, P5, and P7 are the gain adjustment points when the signal gradually increases, and P2, P4, and P6 are the gain adjustment points when the signal gradually decreases. When the receiver thermal noise level is P1, the output signal power of the RF receiving channel is C.

The input signal power of the receiving front end is between P1 and P3: in the initial state, as the input signal power of the receiving front end increases continuously, the output signal power of the RF receiving channel also increases continuously. At this time, the input signal power and output signal power of the receiving front end proportional to each other. When the output signal power of the radio frequency receiving channel is greater than the threshold value A, the received signal strength calculation module 206 adjusts the radio frequency channel gain, and reduces the radio frequency channel gain by X, so that the output signal power of the radio frequency receiving channel is between the threshold value B and A, that is point c.

Thereafter, two situations may occur: one is a situation in which the input signal power of the receiving front end increases, and the other is a situation in which the input signal power of the receiving front end decreases.

The first situation is: that is, the input signal power of the receiving front end is between P3 and P1. When the input signal power of the receiving front end decreases, the output signal power of the RF receiving channel is also continuously decreasing. When the output signal power of the RF receiving channel is less than the threshold When the value is B, the received signal strength calculation module 206 adjusts the radio frequency channel gain to increase the radio frequency channel gain by X, that is, point g. Then, as the input signal power of the receiving front end decreases continuously, the output signal power of the radio frequency receiving channel also decreases continuously.

The second situation is: that is, the input signal power of the receiving front end is between P3 and P5. When the input signal power of the receiving front end increases, the output signal power of the RF receiving channel also increases continuously. When the output signal power of the RF receiving channel increases again to When the threshold value is A, that is, point d, the received signal strength calculation module 206 adjusts the radio frequency channel gain, and reduces the radio frequency channel gain by X, that is, point h.

It can be seen from the above steps that the present invention reduces the adjustment amount of the gain value, which can avoid the frequent switching of the output signal power due to the jitter of the front-end input signal power.

Claims (2)

1, a kind of radio frequency reception channel auto gain control method is characterized in that, sets in advance threshold value A and B, and A is greater than B, and this method comprises:

A. whether judge the current output signal power of radio frequency reception channel greater than threshold value A, if greater than, then the output signal power of radio frequency reception channel is reduced X, and X returns step a greater than 0 and poor less than A and B, otherwise, execution in step b;

Whether the output signal power of b. judging described radio frequency reception channel less than threshold value B, if less than, then the output signal power with radio frequency reception channel increases X, returns step a, otherwise, do not handle, return step a.

2, method according to claim 1 is characterized in that, described X equals 1/2nd times of difference of A and B.

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